Primary intraosseous meningioma of the vertebra: illustrative case

BACKGROUND Primary intraosseous meningiomas (PIMs) are rare, and PIMs of the vertebrae have not yet been reported. The authors report a case of primary meningioma arising from the vertebrae. OBSERVATIONS A 49-year-old man presented with lower back pain and numbness in both lower extremities. Lumbar spine magnetic resonance imaging revealed an L2 pathological fracture with epidural and paraspinal invasion. The patient had undergone a first palliative decompression and fixation surgery, and the diagnosis turned out to be a World Health Organization grade III anaplastic meningioma based on histopathology. The tumor had progressed after first operation and radiation therapy, and the patient was referred to the authors’ institute for excision. The patient had an uneventful postoperative course after a revisional total en bloc spondylectomy of L2. LESSONS The authors present a rare case of PIM of the vertebrae with epidural and paraspinal invasion. Careful preoperative assessment and surgical planning is crucial for successful patient management.

Biomechanics of artificial pedicle fixation in a 3D-printed prosthesis after total en bloc spondylectomy: a finite element analysis

Background This study compared the biomechanics of artificial pedicle fixation in spine reconstruction with a 3-dimensional (3D)-printed prosthesis after total en bloc spondylectomy (TES) by finite element analysis. Methods A thoracolumbar (T10–L2) finite element model was developed and validated. Two models of T12 TES were established in combination with different fixation methods: Model A consisted of long-segment posterior fixation (T10/11, L1/2) + 3D-printed prosthesis; and Model B consisted of Model A + two artificial pedicle fixation screws. The models were evaluated with an applied of 7.5 N·m and axial force of 200 N. We recorded and analyzed the following: (1) stiffness of the two fixation systems, (2) hardware stress in the two fixation systems, and (3) stress on the endplate adjacent to the 3D-printed prosthesis. Results The fixation strength of Model B was enhanced by the screws in the artificial pedicle, which was mainly manifested as an improvement in rotational stability. The stress transmission of the artificial pedicle fixation screws reduced the stress on the posterior rods and endplate adjacent to the 3D-printed prosthesis in all directions of motion, especially in rotation. Conclusions After TES, the posterior long-segment fixation combined with the anterior 3D printed prosthesis could maintain postoperative spinal stability, but adding artificial pedicle fixation increased the stability of the fixation system and reduced the risk of prosthesis subsidence and instrumentation failure.

The most appropriate titanium mesh cage size for anterior spinal reconstruction after single-level lumbar total en bloc spondylectomy: a finite element analysis and cadaveric validation study

Purpose There is little information available regarding the cage diameter that can provide the most rigid construct reconstruction after total en bloc spondylectomy (TES). The aim of this study was thus to determine the most appropriate titanium mesh cage diameter for reconstruction after spondylectomy. Methods A finite element model of the single level lumbar TES was created. Six models of titanium mesh cage with diameters of 1/3, 1/2, 2/3, 3/4, 4/5 of the caudad adjacent vertebra, and 1/1 of the cephalad vertebra were tested for construct stiffness. The peak von Mises stress (MPa) at the failure point and the site of failure were measured as outcomes. A cadaveric validation study also conducted to validate the finite element model. Results For axial loading, the maximum stress points were at the titanium mesh cage, with maximum stress of 44,598 MPa, 23,505 MPa, 23,778 MPa, and 16,598 MPa, 10,172 MPa, 10,805 MPa in the 1/3, 1/2, 2/3, 3/4, 4/5, and 1/1 diameter model, respectively. For torsional load, the maximum stress point in each of the cages was identified at the rod area of the spondylectomy site, with maximum stress of 390.9 MPa (failed at 4459 cycles), 141.35 MPa, 70.098 MPa, and 88.972 MPa, 42.249 MPa, 15.827 MPa, respectively. A cadaveric validation study results were coincided with the finite element model results. Conclusion The most appropriate mesh cage diameter for reconstruction is 1/1 the diameter of the lower endplate of the adjacent cephalad vertebra, due to its ability to withstand both axial and torsional stress. According to the difficulty of large size cage insertion, a cage diameter of more than half of the upper endplate of the caudad vertebrae is acceptable in term of withstand stress. A cage diameter of 1/3 is unacceptable for reconstruction after total en bloc spondylectomy.

Biomechanics of artificial pedicle fixation in a 3D-printed prosthesis after total en bloc spondylectomy: A finite element analysis

Background: This study compared the biomechanics of artificial pedicle fixation in spine reconstruction with a 3-dimensional (3D)-printed prosthesis after total en bloc spondylectomy (TES) by finite element analysis.Methods: A thoracolumbar (T10–L2) finite element model was developed and validated. Two models of T12 TES were established in combination with different fixation methods: Model A consisted of long-segment posterior fixation (T10/11, L1/2) + 3D-printed prosthesis; and Model B consisted of Model A + two artificial pedicle fixation screws. The models were evaluated with an applied of 7.5 N·m and axial force of 200 N. We recorded and analyzed the following: 1) stiffness of the two fixation systems; 2) hardware stress in the two fixation systems; and 3) stress on the endplate adjacent to the 3D-printed prosthesis.Results: The fixation strength of Model B was enhanced by the screws in the artificial pedicle, which was mainly manifested as an improvement in rotational stability. The stress transmission of the artificial pedicle fixation screws reduced the stress on the posterior rods and endplate adjacent to the 3D-printed prosthesis in all directions of motion, especially in rotation.Conclusions: After TES, the posterior long-segment fixation combined with the anterior 3D printed prosthesis could maintain postoperative spinal stability, but adding artificial pedicle fixation increased the stability of the fixation system and reduced the risk of prosthesis subsidence and instrumentation failure.

Total en bloc spondylectomy is worth doing in complete paralysis spinal giant cell tumor, a minimum 1-year follow-up

Objective: To investigate the neurological recovery of Frankel A spinal giant cell tumor (GCT) patients after they had received a Total En Bloc Spondylectomy (TES). Materials and Methods: We retrospectively recorded data of three patients (two females) with mobile spine GCT (T6, T10, and L2) Enneking stage III with complete paralysis before surgery, who had undergone TES in our institute from January 2018 to September 2020. The duration of neurologic recovery to Frankel E was the primary outcome. The intra-operative blood loss, operative time, operative-related complications, and the local recurrence were the secondary outcomes. Results: The duration of suffering from Frankel A to TES surgery was 2 months for the T6 patient, 3 weeks for the T10 patient, and 1 month for the L2 patient. Three patients had achieved full neurological recovery to Frankel E within 6 months after TES (T6 for 5 months, T10 for 3 months, and L2 for 3 months). The average blood loss was 2833.33 ml and the mean operative time was 400 min. Up until the last follow-up (13–25 months), no evidence of local recurrences had been found in any of the three patients. Conclusion: Frankel A spinal GCT patients can achieve full neurological recovery after TES, if the procedure is performed within 3 months after complete paraplegia. TES can effectively control any local recurrences.

Total en bloc spondylectomy combined with the satellite rod technique for spinal tumors

Background Instrumentation failure (IF) is a common complication after total en bloc spondylectomy (TES) in spinal tumors. This study aims to evaluate the clinical outcomes of TES combined with the satellite rod technique for the treatment of primary and metastatic spinal tumors. Methods The clinical data of 15 consecutively treated patients with spinal tumors who underwent TES combined with the satellite rod technique by a single posterior approach from June 2015 to September 2018 were analyzed retrospectively. Radiographic parameters including the local kyphotic angle (LKA), anterior vertebral height (AVH), posterior vertebral height (PVH), and intervertebral titanium mesh cage height (ITMCH) were assessed preoperatively, postoperatively, and at the final follow-up. The visual analog scale (VAS), Oswestry Disability Index (ODI), and American Spinal Injury Association (ASIA) scale were used to assess quality of life and neurological function. The operative duration, volume of blood loss, and complications were also recorded. Results The mean operation time and volume of blood loss were 361.7 min and 2816.7 mL, respectively. During an average follow-up of 31.1 months, 2 patients died of tumor recurrence and multiple organ metastases, while recurrence was not found in any other patients. Solid fusion was achieved in all but one patient, and no implant-related complications occurred during the follow-up. The VAS, ODI, and ASIA scores significantly improved from before to after surgery (P < 0.05). The LKA, AVH, and PVH significantly improved from before to immediately after surgery and to the final follow-up (P < 0.05), and the postoperative and final follow-up values did not significantly differ (P > 0.05). Conclusions TES combined with the satellite rod technique can yield strong three-dimensional fixation and reduce the occurrence of rod breakage, thereby improving the long-term quality of life of patients with spinal tumors.